Hi Mike,
As you can see I put a fair bit of time into that answer thinking that you were a "back-yard-wanna-be" (home brew hopefull??) of which there are plenty in manufacturing, or at least a small operation however that's clearly not the case so sorry about that. I drew my conclusions too fast. Certainly fitting that type of led in an automotive application never been done so no wonder you're excited about it. You'll probably get sued for blinding the drivers behind said bikes! hehehe

Punching for me would be the way to go both on the aluminium heat sink and also the circuit board external shape which I assume will be what holds everything together and also ties it to the body of the light which I assume is plastic.

The only problem I see is that after punching you'll have a jigsaw of pieces and then you must find all the pieces, orientate them and bond them in perfect alignment on the substate. Yes jigs can help but I wonder if it wouldn't be better to punch as suggested above but leave two narrow little bridges on each piece to hold it all together, bond it, place in mill to remove bridges. However that makes one more process so I don't know, just an idea..... I'll think on it a bit today.